Incandescent bulbs are slowly being phased out in favor of more efficient lighting sources. This has led to an increased use of compact fluorescent bulbs which are more efficient than incandescent bulbs, but which tend to contain dangerous gasses, such as mercury. Compact fluorescent bulbs are also affected by ambient temperature and fail reach their peak brightness in colder conditions. Additionally, many people find the color temperature of light emitted by compact fluorescents to not be aesthetically pleasing for many applications, such as household lighting in kitchens, bathrooms, and living rooms; some commercial applications; and the like. Due to the nature of compact fluorescent bulbs, the bulbs always have a frosted appearance, which also tends to reduce the aesthetic appeal of compact fluorescent bulbs. The use of halogen bulbs has also increased; however due to the high temperatures at which halogen bulbs operate they are not highly efficient and may be a fire or burn hazard.
Recent advances in manufacturing light emitting diodes (LEDs) combined with the efficiency and long lifetime of LEDs have led to an increase in the availability and affordability of LED lamps. LED lamps offer advantages over compact fluorescent bulbs including longer lifetime and the absence of dangerous gasses. Also, LED lamps may be configured to emit light at a wide variety of color temperatures.
Both incandescent bulbs and compact fluorescent bulbs emit light into a solid angle of nearly 4π steradians about the bulb. LEDs are inherently a directional light source. Moreover, because LEDs are small, solid state devices, the LEDs tend to be mounted on a circuit board or the like. This means that LED bulbs or LED luminaires tend to only emit light into a solid angle of less than 2π steradians about the bulb or luminaire. Therefore, care must be taken to mount the LED bulbs or luminaires within the lighting fixture such that the light emitted by the LEDs is emitted in a direction that is appropriate for the lighting fixture and/or application. This may result in a lighting fixture which is not aesthetically pleasing. For example, lantern style LED lighting fixtures tend to have the LEDs mounted to the top inner surface of the lighting fixture such that the light is emitted downward into the lantern. This causes the lighting fixture to have an awkward appearance. If the LEDs were simply positioned in the bottom of the fixture shining upward, this directional light beam would not provide any light below the fixture and the majority of light lost into the top of the fixture. Additionally, placing the LEDs in the bottom of the fixture shining up would not be nearly as aesthetically pleasing as the light effect obtained when using a incandescent or halogen clear light bulb.
Additionally, while LEDs are more efficient than incandescent light sources, LED light sources require a mechanism that can be used to dissipate the heat generated by the LEDs. If the heat is not efficiently dissipated, the efficiency of the LEDs or the LED light source may be compromised. Furthermore, improper heat dissipation may cause the LEDs or the LED light source to degrade prematurely.
Thus, there is a need for LED lighting fixtures which are both aesthetically pleasing and provide appropriate heat dissipation.